Flat grind stage assembly for an automatic edge grinder

Abstract

The flat grind stage assembly is programmed so that the grinding wheel is first caused to move along a straight path to form a flat on a wafer while the wafer is held in a stationary position. Thereafter, the grinding wheel is returned to the mid-point of the flat and then moved away from the flat. The wafer is then rotated and grinding commences when the end of the flat is reached so that a circular periphery is ground on the remainder of the wafer while the axis of the grinding wheel remains stationary.

What is claimed is: 
     
       1. A flat grind stage assembly for a grinding machine comprising holding means for rotating a wafer on a fixed axis;   a grinding wheel for grinding a peripheral edge of the wafer;   first means for moving said grinding wheel along a first axis perpendicular to said fixed axis of the wafer for grinding the edge of the wafer during rotation thereof; and   second means for moving said grinding wheel along a second axis perpendicular to said first axis for grinding at least one flat on the edge of the wafer with the wafer in a stationary position.   
     
     
       2. An assembly as set forth in claim 1 which further comprises a processing means connected with said holding means, said first means and said second means for actuating said first means and said second means to grind the peripheral edge of a rotating wafer into a circular shape with at least one flat. 
     
     
       3. An assembly as set forth in claim 2 wherein said processing means is connected to said holding means to stop rotation of the wafer during movement of said grinding wheel along said second axis. 
     
     
       4. In a automatic grinding machine, the combination comprising a grinding wheel for grinding a peripheral edge on a wafer;   a housing having said grinding wheel rotatably mounted therein on a first axis;   a carriage having said housing secured thereto;   first means for moving said carriage along a first path in a plane spaced from and parallel to said first axis to move said grinding wheel along the peripheral edge of a wafer to form a flat thereon; and   second means for moving said carriage along a second path perpendicular to said first path and intersecting with said first axis to move said grinding wheel into engagement with the peripheral edge of a rotating wafer to form a curvilinear edge thereon.   
     
     
       5. An automatic grinding machine as set forth in claim 4 wherein said first axis is a vertical axis and each said path is horizontally disposed. 
     
     
       6. An automatic grinding machine as set forth in claim 4 wherein said first means includes a pair of horizontally disposed parallel guide rails guiding said carriage thereon and a stepper motor connected to said carriage for moving said carriage along said guide rails. 
     
     
       7. An automatic grinding machine as set forth in claim 6 which further comprises a sensor disposed in a predetermined fixed position relative to said guide rails for sensing arrival of said carriage thereat and for emitting a signal in response thereto. 
     
     
       8. An automatic grinding machine as set forth in claim 7 which further comprises a processing means connected to said stepper motor and said sensor for actuating said stepper motor to move said carriage to said fixed position at the beginning of a grinding operation and for thereafter actuating said stepper motor to move said carriage a programmed amount away from said sensor to form a flat on a peripheral edge of a wafer. 
     
     
       9. An automatic grinding machine as set forth in claim 6 wherein said first means includes a rotatable screw rotatably connected to said motor for rotation thereby and threaded into said carriage in rotatable relation. 
     
     
       10. An automatic grinding machine as set forth in claim 6 wherein said second means includes a pair of horizontally disposed parallel support rails, a support housing mounted on said support rails and having said first means secured thereto, and a second motor connected with said support housing for moving said support housing along said support rails. 
     
     
       11. An automatic grinding machine as set forth in claim 10 which further comprises a sensor disposed in a predetermined fixed position relative to said guide rails for sensing arrival of said carriage thereat and for emitting a signal in response thereto. 
     
     
       12. An automatic grinding machine as set forth in claim 11 which further comprises a processing means connected to said stepper motor and said sensor for actuating said stepper motor to move said carriage along said guide rails to said sensor at the beginning of a grinding operation and for thereafter actuating said stepper motor to move said carriage along said guide rails a programmed amount away from said sensor to form a flat on a peripheral edge of a wafer, said processing means being connected to said second motor to actuate said second motor after formation of a flat to move said grinding wheel relative to the wafer to grind a curvilinear peripheral edge thereon. 
     
     
       13. An automatic grinding machine as set forth in claim 4 which further comprises a stationary housing having said grinding wheel movably disposed therein in sealed relation. 
     
     
       14. An automatic grinding machine as set forth in claim 13 which further comprises means for directing a flow of coolant into said housing adjacent said grinding wheel. 
     
     
       15. An automatic grinding machine comprising holding means for positioning a wafer on a fixed axis of rotation;   a grinding wheel for grinding a peripheral edge on a held wafer;   a carriage having said grinding wheel rotatably mounted thereon;   first means for moving said carriage along a first path in a plane spaced from and parallel to said fixed axis to move said grinding wheel along the edge of the wafer to form a flat thereon; and   second means for moving said carriage along a second path perpendicular to said first path and intersecting with said first axis to move said grinding wheel into engagement with the peripheral edge of a rotating wafer to form a curvilinear edge thereon.   
     
     
       16. An automatic grinding machine as set forth in claim 15 which further comprises a processing means connected with said holding means, said first means and said second means for actuating said first means to form a flat on the wafer and thereafter actuating said holding means and said second means to rotate the wafer while forming a curvilinear periphery thereon. 
     
     
       17. An automatic grinding machine as set forth in claim 16 which further comprises a sensor disposed in a predetermined fixed position relative to said first path for sensing arrival of said carriage thereat and for emitting a signal in response thereto. 
     
     
       18. An automatic grinding machine as set forth in claim 17 wherein said processing means is connected to said sensor to actuate said first means to move said carriage to said sensor at the beginning of a grinding operation and to thereafter actuate said first means to move said carriage a programmed amount away from said sensor along said first path to form a flat on the wafer. 
     
     
       19. An automatic grinding machine as set forth in claim 18 wherein said first means includes a pair of horizontally disposed parallel guide rails guiding said carriage thereon and a stepper motor connected to said carriage for moving said carriage along said guide rails. 
     
     
       20. An automatic grinding machine as set forth in claim 18 which further comprises a stationary housing having said grinding wheel movably disposed therein in sealed relation. 
     
     
       21. In a automatic grinding machine, the combination comprising holding means for holding a wafer on a fixed axis;   a grinding wheel for grinding a peripheral edge on the wafer;   a housing having said grinding wheel rotatably mounted therein on a first axis;   a carriage having said housing secured thereto;   first means for moving said carriage from a defined "home" position along a first path in a plane spaced from and parallel to said first axis to move said grinding wheel along the peripheral edge of a wafer to form a flat thereon and to thereafter reverse said carriage to move said grinding wheel to a mid-point of the flat; and   second means for moving said carriage along a second path perpendicular to said first path and intersecting with said first axis to move said grinding wheel into engagement with the peripheral edge of a rotating wafer to form a curvilinear edge thereon.   
     
     
       22. An automatic grinding machine as set forth in claim 21 wherein said first axis is a vertical axis and each said path is horizontally disposed. 
     
     
       23. An automatic grinding machine as set forth in claim 21 which further comprises a sensor disposed in a predetermined fixed position for sensing arrival of said carriage at said "home" position and for emitting a signal in response thereto. 
     
     
       24. An automatic grinding machine as set forth in claim 23 which further comprises a processing means connected to said first means and said sensor for actuating said first means to move said carriage to said fixed position at the beginning of a grinding operation and for thereafter actuating said first means in response to said signal to move said carriage a programmed amount away from said sensor to form a flat on a peripheral edge of a wafer. 
     
     
       25. A method of grinding a wafer comprising the steps of holding a wafer on a fixed axis;   moving a grinding wheel along a first path in a plane spaced from and parallel to said fixed axis to move said grinding wheel against the edge of the wafer to form a flat thereon;   thereafter moving said grinding wheel along said first path in a reverse direction to a mid-point of the flat; and   moving said grinding wheel along a second path perpendicular to said first path and intersecting with said fixed axis to position said grinding wheel in spaced relation to the flat; and thereafter rotating the wafer while engaging said grinding wheel with the edge thereof to form a curvilinear edge thereon.